Why cannot create partitioning table

问题

I'm trying to create simple table with partitions.

this is my command:

CREATE TABLE measurement (
    city_id         int not null,
    logdate         date not null,
    peaktemp        int,
    unitsales       int
) PARTITION BY RANGE (logdate);

this is the error I got:

SQL Error [42601]: ERROR: syntax error at or near "PARTITION"

Unable to understand with is the problem..

I am using PostgreSQL 9.6.3

回答1:

"Declarative table partitioning", that is partitioning as a first-class feature of the DBMS with its own syntax, was added in PostgreSQL 10.

In earlier versions, you can achieve the same effect with a bit more effort using "table inheritance". There is a page in the manual describing how to do this manually, summarised as:

1. Create the "master" table, from which all of the partitions will inherit.
2. Create several "child" tables that each inherit from the master table.
3. Add table constraints to the partition tables to define the allowed key values in each partition.
4. For each partition, create an index on the key column(s), as well as any other indexes you might want.
5. Optionally, define a trigger or rule to redirect data inserted into the master table to the appropriate partition.
6. Ensure that the constraint_exclusion configuration parameter is not disabled in postgresql.conf. If it is, queries will not be optimized as desired.

To make this easier, if you can't upgrade to version 10, you can use an extension such as pg_partman which gives you additional functions for setting up and managing partition sets.

回答2:

Here is the example of automatically creating monthly partition for 9.6 version, may be compatible with other versions:

`----------Function to create partitions by system------------------
CREATE OR REPLACE FUNCTION schema.insert_function()
RETURNS TRIGGER
AS $$
DECLARE
partition_date TEXT;
partition_schema TEXT;
partition_name TEXT;
start_of_month TEXT;
end_of_month TEXT;
BEGIN
partition_date := to_char(NEW.created_dtm,'YYYY_MM');
partition_schema := 'temp';
partition_name := 'patition_name_' || partition_date;
start_of_month := to_char((NEW.created_dtm),'YYYY-MM'|| '-01');
end_of_month := to_char((NEW.created_dtm + interval '1 month'),'YYYY-MM'|| '-01');
IF NOT EXISTS
(SELECT 1
 FROM   information_schema.tables
 WHERE  table_name = partition_name
 AND table_schema = partition_schema)
THEN
EXECUTE 'CREATE TABLE '|| partition_schema ||' . '|| partition_name ||' (check (created_dtm >= ''' || start_of_month || ''' and created_dtm < ''' || end_of_month || ''' ), ' || 'LIKE master_schema.master_table  INCLUDING ALL) INHERITS (master_schema.master_table)';
EXECUTE format('ALTER TABLE %I.%I OWNER TO role1', partition_schema, partition_name);
EXECUTE format('GRANT SELECT ON TABLE %I.%I TO read_only_role', partition_schema, partition_name);
EXECUTE format('GRANT INSERT, SELECT, UPDATE, DELETE ON TABLE %I.%I TO read_write_role', partition_schema, partition_name);
EXECUTE format('CREATE INDEX ON %I.%I(column1, column2, column3)', partition_schema, partition_name);
EXECUTE format('CREATE UNIQUE INDEX ON %I.%I(column4)', partition_schema, partition_name);
........
RAISE NOTICE 'A partition has been created %.%', partition_schema, partition_name;
RAISE NOTICE 'All necessary indices are created on %.%', partition_schema, partition_name;
END IF;
EXECUTE format('INSERT INTO %I.%I VALUES($1.*)', partition_schema, partition_name) using NEW;
RETURN NULL;
END
$$
LANGUAGE plpgsql;

ALTER FUNCTION schema.insert_function()
OWNER TO super_user;

-----------------------------------------Trigger on master table--------------
CREATE TRIGGER insert_trigger
BEFORE INSERT
ON master_schema.master_table
FOR EACH ROW
EXECUTE PROCEDURE schema.insert_function();`

来源：https://stackoverflow.com/questions/50131797/why-cannot-create-partitioning-table